This invention relates to a dressing or preserving liquid filling unit for vacuum filling and the like machines.
As is known, canned food products, such as fruit, vegetables and the like, are immersed in a liquid, commonly called "dressing liquid", which may be juice from the product itself, a product preparation liquid, syrup, a conservation liquid, and include liquids having different viscosities and liquids with solid suspensions.
In effecting this type of packaging, it is current practice to first introduce the dripped product into the can, thereafter, by means of automatic filling machines called toppers, the dressing liquid is introduced in a desired amount.
Such packaging machines are set up to carry out a given sequence of operations including the creation of a vacuum in the can intended to contain the dripped product, the filling of the can with dressing liquid--which is effected by "suction", that is through the vacuum in the can drawing in the dressing liquid from a suitably arranged dressing liquid reservoir.
After the filling step, the can is subjected to a dressing liquid topping and level adjusting step whereby the dressing liquid is brought to the exact desired level, thereafter the vacuum is removed as may be still present inside the can by placing the latter in communication with the atmosphere.
In some cases, the topping step may be omitted altogether, as being unnecessary when operating with a low temperature dressing liquid and without any risk of its tending to foam when vacuumed.
All these processing steps are carried out on carousel-type machines which are equipped with a plurality of valving elements comprising a lower body sealingly associable with a can to be filled and an upper body which is mounted pivotally above the lower body and is rotated to sequentially establish external connections, that is connections with the vacuum source and dressing liquid reservoir for carrying out the cited steps.
According to current practice, the rotation of the upper body is generally accomplished by providing an upwardly exending axial rod above the upper body which is terminated with a cross or spider element effective, during the movement of the valving elements on the carousel, to successively engage with a cam which causes, at a suitable time, a rotation by 90.degree. or submultiple of 90.degree. of the upper body with respect to the lower body, thus providing the transition from one processing step to the next.
This approach, while satisfactory in theory, is quite objectionable from a practical standpoint in that the rotation of the upper body relatively to the lower one, as accomplished through the spider interfering with the cam, results in a series of impacts of the spider against the cams, which produces considerable noise, which noise becomes specially annoying and even intolerable owing to the topper machines including a fairly high number of valving elements or members which are brought into operation in accordance with a continuous operating cycle, so that the noise produced by the continued impacts may be actually a deafening one.
Another problem connected with the cited means of actuation of the upper body resides in that by achieving the rotational movement through a continuous series of impacts both the cams and spiders are subjected to considerable wear, so that the machine requires continued servicing, which appreciably affects the production cycles.
A further drawback is that the continued succession of impacts unavoidably results in the separation of metal particles which may float in the air and get into the can along with the food product, which thing is obviously unacceptable.
Moreover, the completion of rotational movements between one step and the next, generally amounting to 90 degrees, of the upper body relative to the lower body, in addition to lowering the production rate owing to the transitions from one step to the next, also causes a farily appreciable amount of wear at the contact area between the lower and upper bodies, which contact must obviously occur in a tight sealed condition to prevent the escape of dressing liquid, as well as at the other elements connected to the upper body.